Implantable cardiac rhythm management devices are an effective treatment in managing irregular cardiac rhythms in particular patients. Implantable cardiac rhythm management devices are capable of recognizing and treating arrhythmias with a variety of therapies. To effectively deliver these therapies, however, cardiac rhythm management devices must first accurately sense and classify an episode.
In order to apply the proper therapy in responding to an episode, some cardiac rhythm management devices compare sensed cardiac signals to a previously stored “template” representing normal sinus rhythm (NSR) or other “template” frequently intended to represent the patient's NSR. This stored NSR template must accurately characterize a patient's true NSR in order to be used in a process that properly identifies potentially fatal deviations from normal cardiac activity.
Problems arise when the cardiac rhythm management device inaccurately compares a sensed cardiac complex to a stored NSR template, and as a result, misclassifies the sensed cardiac complex. The severity of this problem escalates if the cardiac rhythm management device inappropriately delivers therapy due to the misclassification. In illustration, when a particular group of sensed complexes are erroneously compared to a stored template because of an improper alignment to the template, a cardiac rhythm management device may mistakenly classify these sensed complexes as a mismatch and even possibly as a tachyarrhythmia.
For the reasons stated above, and for other reasons stated below, which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for providing a reliable system to generate templates for comparison with sensed cardiac events to accurately classify and, if indicated, treat the cardiac rhythm a patient is experiencing.